Over the years, there have been numerous variations of locking devices for a multitude of applications. Typically, a locking device is used to secure objects together, whether it be two independent items, a door for an enclosure, or the like. Moreover, a wide variety of locking mechanisms have been employed, including key actuated locks and combination locks, all of various constructions.
A widely used locking device is known as a padlock. The prior art padlock works adequately for a number of conventional applications wherein the span of objects to be secured is relatively short or where the span can be fitted with a hasp. However, numerous short comings of padlocks become apparent when a padlock is sought to be used in applications wherein two objects of thick cross-sections are to be secured. Examples of such conventional applications include those where telescopically joined round or square tubing members need to be secured together. Another example is where perpendicular or axially cross-bolting of gates and doors require a substantially rod-like locking device.
As a result of the need for rod or elongated shackle locking devices, various devices have been developed to penetrate multiple surfaces having aligned through bores for the purpose of securing those objects together. Once such example is found in U.S. Pat. No. 2,677,261 issued May 1954 to Jacobi. The Jacobi patent, a complex locking device is taught in order to prevent actuation of a refrigerator door handle. Another example of a rod locking device is found in U.S. Pat. No. 4,576,021 issued Mar. 18, 1986 to Holden. Holden discloses a locking rod device having a rectangular locking head that is somewhat bulky and non-symmetrical. In the Holden locking device, a radially extendable locking pin engages a circumferential opening in the latch portion of the shackle in order to retain the shackle and locking head together. The bulky nature of this lock head design, however, makes it disadvantageous in use where only limited space is available. In addition, where the locking pin is spring loaded, the locking structure of Holden is prone to false locking, that is, the engagement of the locking head and shackle without an actual locked state occurring. Thus, the locking head may fall off during use.
Several additional types of straight shackle locks have been developed wherein the latched portion of the shackle is threadably received in a screw-type lock. Examples of these locks are described in U.S. Pat. No. 4,619,122 issued Oct. 28, 1986 to Simpson as well as in U.S. Pat. No. 4,711,106 issued Dec. 8, 1987 to Johnson. These types of locks, however, tend to be inconvenient and cumbersome to use due to the threaded nature of their locked mechanisms. Specifically, the key actuable locking head described in these two patents require a large number of key rotations in order to thread and fully secure the locking head portion onto the straight shackle. The inconvenience and difficulty of threaded lock systems is compounded when the lock is located in tight or difficult to access areas. Further, the threaded screw lock are especially prone to corrosion and seizure due to the small dimensioning of the threads.
The majority of the locking structures described in the prior art fail to employ suitable seals or other structures, such as caps or protective devices to limit access of unwanted substances such as dirt and moisture into the keyway or into the locking region. In U.S. Pat. No. 5,664,445 issued Sep. 9, 1997 to Chang, a sealing ring is provided on the shackle latch portion. While the Chang patent does address the importance of limiting the access of dirt and moisture into the locked mechanism, the solution offered in the Chang patent has some drawbacks. Due to the location of the seal on the end portion of the shackle, the seal is completely exposed. Since it is of larger diameter than the shank of the shackle, the slidable engagement of the shackle through aligned bores of two objects exposes the oversized diameter of the seal to attack by the rough edges or other sharp corners of the bores due to its oversized diameter. Thus, the seal can become damaged due to the snagging or rubbing of the seal against the aligned holes.
Accordingly, there remains a need for improved locking structures of a rod or cable type nature which can effectively lock objects together. There is a need for such locking mechanisms to have suitable seals and protective structures to prevent ingress of unwanted substances, such as dirt and moisture, into the locking mechanism. There is a further need for locking structures that reduce the tendency for false locking conditions.